Add initial borg backup server

To catch up -- because this work is moving slowly ... the two backup
servers are currently the vexxhost and RAX ORD hosts.  The vexxhost
node is deployed with Ansible on Bionic, but the old ORD host still
needs to be upgraded and moved out of puppet.  Instead of dealing with
the unmaintained bup and getting it to work on the current LTS Focal,
we are doing an initial borg deployment with plans to switch to it
globally.

This adds the backup02.ca-ymq-1.vexxhost.opendev.org to the inventory
and borg-backup-server group, so it will be deployed as a borg backup
server (note, no hosts are backing up to it, yet).

To avoid the original bup roles matching, we restrict the
backup-server group to backup01.ca-ymq-1.vexxhost.opendev.org
explicitly.

Change-Id: Id30a2ffad75236fc23ed51b2c67d0028da988de5

inventory/base/hosts.yaml

@@ -56,6 +56,13 @@ all:
         region_name: ca-ymq-1
       public_v4: 199.204.45.119
       public_v6: 2604:e100:1:0:f816:3eff:feab:d678
+    backup02.ca-ymq-1.vexxhost.opendev.org:
+      ansible_host: 199.204.45.196
+      location:
+        cloud: openstackci-vexxhost
+        region_name: ca-ymq-1
+      public_v4: 199.204.45.196
+      public_v6: 2604:e100:1:0:f816:3eff:fe83:a5e5
     backup01.ord.rax.ci.openstack.org:
       ansible_host: 23.253.20.173
       location:

inventory/service/groups.yaml

@@ -34,7 +34,9 @@ groups:
     - storyboard01.opendev.org
     - translate01.openstack.org
   backup-server:
-    - backup[0-9]*.opendev.org
+    - backup01.ca-ymq-1.vexxhost.opendev.org
+  borg-backup-server:
+    - backup02.ca-ymq-1.vexxhost.opendev.org
   cacti: cacti[0-9]*.open*.org
   certcheck:
     - cacti[0-9]*.open*.org